1. Field of the Invention
This invention relates to the field of self resealable container closures and particularly concerns a closure or cap which is self-resealing after perforation with a blunt tipped implement such as a laboratory pipette. The invention also concerns improvements in clinical laboratory practices resulting from use of the self resealing container closure in specimen containers used in the collection and handling of medical specimens such as urine specimens.
2. State of the Prior Art
Many vials and containers are available with closures, such as a septum of elastomeric material, which are penetrable by a sharp pointed metal needle such as a hypodermic needle, and which maintain a good seal after being pierced by the needle. Those closures, however, cannot be penetrated with relatively blunt tip ends such as those found on liquid transfer pipettes commonly used in clinical laboratories for transferring specimen liquids such as blood and urine.
No containers are known having an elastomeric septum puncturable by such implements and which is also self-resealing following such puncture in order to restore a sufficiently effective liquid tight seal for safe handling and storage of the remaining specimen material at the clinical laboratory location.
Blood and urine specimens are collected routinely during medical examinations in both outpatient and clinical settings. The individual specimens once collected at the direction of an attending physician is forwarded to a clinical laboratory location which typically is remote from the specimen collection site.
In a typical urine collection procedure, a specimen container is handed to the patient, who then deposits the specimen in privacy. The container vessel may have a screw-on or snap-on cap which may be replaced by the patient after depositing the specimen. The closed container is then handed to a nurse or other medical attendant, who arranges for transfer of the container to the laboratory location. The laboratory location may be in the same building or complex, in the case of a hospital, or may be at a considerable distance across town or even in another city if the specimen was taken at a physician's private office. In either case, some transport of the specimen container is involved, during which it is important to safeguard the specimen against contamination while avoiding any leakage of the specimen liquid from the container. Both these objectives call for a reliable liquid tight seal between the cap and the container.
When received at the clinical location, the specimen container is transferred to a laboratory technician who draws a sample from the clinical specimen in the container. The sample is then subjected to the analytical procedure requested by the attending physician.
The current practice in clinical laboratories is to draw the analytical sample from the specimen container by means of a single use disposable plastic pipette. This pipette is similar to an eye dropper in that it includes a squeeze bulb attached to the upper end of a holding tube, the lower end of which is drawn out to form an elongated tip portion of reduced diameter terminating in an open tip end. The laboratory technician opens the container by manually unscrewing or otherwise removing the container cap, introduces the tip of the pipette into the open container vessel, immerses the tip in the liquid specimen, and aspirates the analytical sample into the holding tube by squeezing and releasing the bulb of the pipette.
The plastic transfer pipettes normally used for this purpose are intended to be used only once and discarded after that single use to prevent cross contamination of successive specimens processed in the laboratory. In the interest of economy, these pipettes are therefore molded in a relatively flexible, soft thermoplastic material which permits the squeeze bulb to be formed integrally with the holding tube and the drawn out tip. The result is that the tip portion of the pipette is rather flexible and is readily bent sideways. A typical transfer pipette of this type has a holding tube which is 2.5″ in length by approximately ¼″ in diameter, a tapering portion approximately 1 and ⅛″ in length at the lower end of the holding tube, terminating in a tip portion 1″ in length and approximately ⅛″ in outside diameter. The tip opening is approximately circular and the tip end is cut square or perpendicular to the longitudinal dimension of the tip portion. At the upper end of the holding tube, the squeeze bulb is approximately 1.25″ in length and about ½″ in diameter. The holding tube portion of the pipette can be squeezed flat between two fingers with little effort, and the thinner tip section can be bent sideways very easily, tending to return to a generally straight original condition when released. The wall of the tip portion at the tip opening is about 1/32″ in thickness. If the pipette is grasped at its mid-portion, along the holding tube portion, and the tip end is pressed against a hard surface, the tip portion of the pipette bends sideways with the application of little manual force applied axially along the pipette and normally to the hard surface. These single use soft plastic transfer pipettes are widely used in clinical laboratories and have proven adequate in regard to economics and functionality for their intended purpose.
Some clinical laboratories prefer to use pipetters with disposable tips. Pipetters are syringe-like devices with a plunger which, when depressed, draws a measured, preset amount of fluid into the barrel to the pipetter through a plastic tip fitted onto the end of the pipetters draw tube. The tip can be ejected from the pipetters by pressing a handle or lever provided for this purpose, without the user touching the tip. A new plastic tip is then fitted onto the pipetter for drawing the next sample, and avoid cross-contamination between successive samples. Such pipetters are widely used in laboratories and are available from many different manufacturers. The disposable plastic tips for the pipetters typically are of elongated conical shape, tapering to a circular tip opening. The open tip end is cut across the long axis of the tip to form a blunt tip end which presents the full thickness of the tip wall transversely to that axis. The open tip end diameter may be about 3/32ds of an inch, with a tip opening of about 1/32nd inch. The length of the disposable tip may be about 3⅜ths inch and the top end about 5/16ths inch.
The open tip end of a disposable plastic pipetter tip may be of comparable dimension to the open tip end of a single use disposable sampling pipette, the main difference being that the plastic pipetter tip is relatively stiff and does not flex readily sideways when pressed against a firm surface.
Clinical urine samples are processed and analyzed in large numbers, with larger clinical laboratories handling thousands of such samples every day. Currently, each of the specimen containers must be manually opened by laboratory personnel in order to draw the analytical samples. Opening and recapping of many such containers constitutes a substantial component of the total labor involved in processing the clinical specimens at the laboratory. Also, the repetitive motion involved in unscrewing and replacing the caps has been known to stress the hand and wrist of laboratory personnel to the point of disability. Furthermore, the open specimen containers pose a risk of contamination of specimens, contamination of the laboratory environment, loss of specimens through accidental spillage, and possible infection of personnel.
It is therefore desirable to provide a method for handling and processing urine and other liquid medical specimens which eliminates the need for opening and closing the specimen containers at the clinical laboratory location. It is further desirable to accomplish this objective with a minimum of change and disruption to existing equipment, supplies and procedures to which laboratory personnel have grown accustomed. In particular, it is desirable to provide specimen containers which can be accessed without uncapping with either the disposable plastic pipetter tips or the disposable plastic transfer pipettes currently in widespread use.
Once an analytical sample is drawn from the specimen container, the container with the remaining specimen material is either discarded, if no further need for the material is contemplated, or is stored against the possible need for additional future analysis of the remaining specimen material. For this reason, it is also important that the closed specimen container maintain an effective seal against spillage and significant leakage during such handling and storage even after an initial sample has been taken of the liquid contents.
For these and other reasons, improvement is needed in the specimen containers used for this purpose and in the handling of the clinical urine specimens.